The point is that a night of separation can be passed only
in weeping. When the tears fall like rain, then a person can't see anything
out of his eyes. When the tears are flowing, then the terrifying darkness
of the night of separation will become visible. And when that happens, then
the eyes will be suitably established as the wicks of candles. (220)

FWP:

Here's a beautiful deployment of classic ghazal imagery.
A stream of bloody tears from the eyes is seen as the melting flow of wax
from two candles that have been lit. Look at the affinities:

=the candle's 'tears' of melting wax are a sign that it's self-consuming,
as are the desperate lover's tears of blood

=the candle's hot 'tears' are generated by a flaming wick
that burns at its center, just as the lover's tears issue from his burning
heart

=the candle will be burnt-out and 'dead' by morning, just
as the lover can hardly hope to outlive the endless night of separation

=the bright blood-red tears will be imagined by the lover
to glow like lighted candles in the darkness of the night of separation

Of course, the lover knows his tears won't really bring him
any light-- he will only 'consider' [samajhnaa] that
they do, by imagining them as candles. We glimpse the depth of his darkness,
in which the only light is a deliberately, self-deceivingly imagined one--
and a doomed one, since by imagining his eyes as candles he imagines them
as burnt-out and blind by morning. But does that even matter? In such a night,
can he even imagine morning at all? (Compare {169,1}.)

We also have a subtle back-and-forth interplay between water and fire, two of the basic elements of the cosmos. A 'stream' of liquid blood will 'flow' steadily out of the eyes, the way liquid wax streams down the side of the candle. But the melting in both cases is a direct consequence of burning: the fiery glow of the 'two candles' of the eyes will 'illumine' the night (or at least, so the lover will imagine). Who can tease apart all the similarities and oppositions in this intertwined imagery?

As a final touch, the lover is seeking to illumine a shaam-e
, 'night of', with sham((e;N , 'candles'. This
isn't exactly a rhyme, but surely it counts as an evocation. Similarly, in the first line we have bahne do , and in the second sham((e;N do -- another verbal echo, with the do of course clevery repurposed.